During endodontic treatment, an endodontic file is used for the debridement of an infected pulp tissue. The endodontic file is mostly made of a metal alloy, e.g. a nickel-titanium (Ni—Ti) alloy, but usually exhibits fatigue problems. For this reason, when the endodontic file is placed in the root canal of a patient in need of the treatment, the file is likely to be fractured when rotated in the root canal for a long period. Upon fracture, a dentist must stop the treatment at once and try to remove the fraction from the root canal. This not only extends the treatment period, but also possibly hurts the patient when the fraction can't be easily removed.
Therefore, there is a need to solve the fatigue problem exhibited in the conventional endodontic file.